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 Table of Contents     
CASE REPORT
Year : 2011  |  Volume : 26  |  Issue : 1  |  Page : 34-35  

Incidental detection of clinically occult follicle stimulating hormone secreting pituitary adenoma on whole body 18-Fluorodeoxyglucose positron emission tomography-computed tomography


1 Department of Nuclear Medicine and PET-CT, Jaslok Hospital and Research Centre, Mumbai, India
2 Department of Radiology, Jaslok Hospital and Research Centre, Mumbai, India

Date of Web Publication7-Sep-2011

Correspondence Address:
Prathamesh Joshi
Department of Nuclear Medicine and PET-CT, Jaslok Hospital and Research Centre, Worli, Mumbai - 400 026
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0972-3919.84611

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   Abstract 

A 73-year-old man, known case of Hodgkin's lymphoma, underwent 18-Fluorodeoxyglucose positron emission tomography-computed tomography (18-FDG PET-CT) for post-chemotherapy evaluation of the disease status. The scan revealed focal increased FDG uptake in pituitary fossa. The CT images showed homogenously enhancing pituitary lesion causing expansion of the sella. A possibility for the presence of pituitary adenoma was raised in the report. Hormonal assay of the patient showed raised follicle stimulating hormone (FSH) level of 18 IU/ml (normal range for males up to 5 IU/ml). All the other pituitary hormones were within the normal range. Nuclear magnetic resonance (NMR) imaging of brain showed a pituitary lesion with expanded sella pushing the optic chiasma superiorly. NMR findings confirmed the presence of pituitary macroadenoma. A final diagnosis of FSH secreting pituitary macroadenoma was made.

Keywords: 18-Fluorodeoxyglucose positron emission tomography-computed tomography, follicle stimulating hormone, nuclear magnetic resonance, pituitary adenoma


How to cite this article:
Joshi P, Lele V, Gandhi R. Incidental detection of clinically occult follicle stimulating hormone secreting pituitary adenoma on whole body 18-Fluorodeoxyglucose positron emission tomography-computed tomography. Indian J Nucl Med 2011;26:34-5

How to cite this URL:
Joshi P, Lele V, Gandhi R. Incidental detection of clinically occult follicle stimulating hormone secreting pituitary adenoma on whole body 18-Fluorodeoxyglucose positron emission tomography-computed tomography. Indian J Nucl Med [serial online] 2011 [cited 2019 Dec 10];26:34-5. Available from: http://www.ijnm.in/text.asp?2011/26/1/34/84611


   Introduction Top


We report a case where incidental 18-Fluorodeoxyglucose (18-FDG) uptake in pituitary fossa was noted in positron emission tomography-computed tomography (PET-CT), which on further investigations was found to be clinically occult follicle stimulating hormone (FSH) secreting pituitary macroadenoma.


   Case Report Top


A 73-year-old man, known case of Hodgkin's lymphoma, underwent 18-FDG PET-CT for post-chemotherapy evaluation of the disease status. The scan revealed focal increased FDG uptake in pituitary fossa [Figure 1]a and b. The Maximum Standardized Uptake Value was 2.1 cm 2 /ml. The sagittal reformatted CT image [Figure 2]a showed homogenously enhancing pituitary lesion causing expansion of the sella, and axial contrast CT image [Figure 2]b showed mildly enhancing rounded lesion in the sella abutting the tuberculum and dorsum sella anteriorly and posteriorly. A possibility for the presence of pituitary adenoma was raised in the report.
Figure 1: (a and b) FDG PET images showing focal increased FDG uptake in the pituitary fossa

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Figure 2: (a and b) CT images demonstrating mildly enhancing rounded lesion in the sella

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Nuclear magnetic resonance (NMR) imaging of brain confirmed the presence of pituitary macroadenoma. High-resolution, T1-weighted, contrast-enhanced, fat-suppressed sagittal image [Figure 3]a showed the pituitary lesion, with expanded sella pushing the optic chiasma superiorly, and high-resolution, T1-weighted, contrast-enhanced, fat-suppressed axial image [Figure 3]b showed homogenously enhancing sellar lesion abutting the cavernous segment of bilateral internal carotid arteries. Hormonal assay of the patient showed raised FSH level of 18 IU/ml (normal range for males up to 5 IU/ml). All the other pituitary hormones were within the normal range. A diagnosis of clinically occult FSH secreting pituitary macroadenoma was made.
Figure 3: Fat-suppressed sagittal NMR image (a) showing pituitary lesion with expanded sella pushing the optic chiasma superiorly and high-resolution, T1-weighted, contrast-enhanced, fat-suppressed axial image (b) showing enhancing sellar lesion

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   Discussion Top


Incidental pituitary FDG uptake is an extremely rare finding. A study revealed that the incidence of focally increased FDG uptake in pituitary is only 0.073%. [1] The pituitary adenoma may have high FDG uptake. [2] The mean SUV max calculated without correction for partial volume effect for macroadenomas is reported to be significantly higher than the SUV max for microadenomas. [1] Pituitary adenomas are the most common cause of pituitary hormone hypersecretion and hyposecretion syndromes in adults. They account for around 15% of all intracranial neoplasms. [3] Isolated gonadotropin secreting pituitary adenoma with increased levels of circulating FSH, as in our case, is a very rare occurrence. [4]

Our case demonstrates the importance of further evaluations, including hormone assays and NMR imaging of the pituitary, to diagnose clinically occult pituitary adenoma when incidental increased pituitary FDG uptake is noted.

 
   References Top

1.Jeong SY, Lee SW, Lee HJ, Kang S, Seo JH, Chun KA, et al. Incidental pituitary uptake on whole-body F-18 FDG PET/CT: A multicentre study. Eur J Nucl Med Mol Imaging 2010;37:2334-43.  Back to cited text no. 1
    
2.Langleben DD, Segall GM. PET in differentiation of recurrent brain tumor from radiation injury. J Nucl Med 2000;41:1861-7.  Back to cited text no. 2
    
3.Shlomo Melmed, J Larry Jameson. Disorders of the anterior pituitary and hypothalamus. In Kasper DL, Braunwald E, Fauci AS, et al. Harrison's Principles of Internal Medicine (16 th ed.). New York, NY: McGraw-Hill. pp. 2076-97.  Back to cited text no. 3
    
4.Koteshwara M, Nick V. A case of FSH secreting pituitary adenoma. Endocr Abstracts 2009;19:256.  Back to cited text no. 4
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]


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